It means you can't get through to delivery date (8)
I believe the answer is:
deadline
'delivery date' is the definition.
The answer and definition can be both related to time as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'it means you can't get through' is the wordplay.
I cannot quite understand how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
'through' could be 'in' and 'in' is found in the answer.
This explanation may well be incorrect...
'to' acts as a link.
Can you help me to learn more?
(Other definitions for deadline that I've seen before include "Time-limit as for journalist's copy" , "Time by which task must be completed" , "Target time" , "Ideal end (anag)" , "a writer may have to meet" .)